Aquaculture is used increasingly for raising or growing and harvesting aquatic species for a variety of uses, including seeding for repopulating natural environments, stocking recreational resources for sport, supplying species for use in controlling other species in certain environments, and for use as food, for example. Many conventional aquaculture systems are known and are supplied for a variety of species in situations, such as growing or sustaining life in natural environments, growing or sustaining life in outer space and growing and sustaining life in man-made systems. Generally, aquatic systems can be classified in one of two ways: closed or open systems. Open systems are most easily typified by natural environments, such as lakes and streams. Closed systems may be quasi-closed systems, such as outdoor fish raceways where a portion of the output may be recycled as part of the new input, but the system is subject to an otherwise natural environment, and totally closed systems, such as an aquarium and those used in outer space and laboratory environments. Regardless of which system is utilized, an organism's optimal growth and survival is directly related to that organism's environment and nutrition. In a truly closed system, the environment of an organism must be monitored and regulated to provide the optimal parameters for the organism's survival. Even open systems must allow for removal of pollutants and waste by-products from the system to assure organism viability.
It is generally recognized in the aquaculture industry that closed systems provide a more convenient way to control the various parameters for successful organism growth. To remove harmful waste products and pollutants, such as nitrogenous waste and fecal matter excreted by vertabrates, for example, one prevalent method is the use of biological filters. Aquaculture systems for raising fish, other aquatic life and/or bacteria utilize biological filters to remove or convert to nontoxic products nitrogenous waste and other undesirable contaminants. Biological filtration is typified by rotating biological filters, trickle filters, fluidized beds, bead filters and other apparatus in which the contaminant-absorbing or converting bacteria and/or plant forms are contained.
The problem with biological filtration is the tendency or, some would say, the inevitability of such a system crashing or destroying itself following a variety of complex chemical and biological processes. For example, where fish are raised in a closed system environment, the respiratory or excretory by-products, if allowed to concentrate and convert to toxic substances, ultimately doom the system to failure, despite the use of biological filtration. Even in a flow-through (i.e., open) system, where the by-products and the pollutants they form are theoretically continually diluted and flushed away, it is questionable whether such flushing is sufficient to remove the toxic agents to a point where the primary or target organism desired ("primary organism" as more particularly defined hereinafter) is successfully maintained and allowed to grow.
Conventional biological filters for use in closed aquaculture systems generally require large surface areas for nitrifying bacteria and other bacteria to grow. However, biological filters are non-specific. That is, not only are biological filters inhabited by nitrifying and other desired bacteria, but many disease-causing bacteria, along with undesirable or useless bacteria, fungi, molds and viruses, can infect and inhabit the biological filter. Considering the bacteria, for example, once the population of aerobic bacteria increases, a biological slime layer is formed, which adds contaminants to water or other aqueous medium passing through the filter. Aerobic bacteria typically present throughout this slime layer will lyse and release their own respiratory and internal substances into the system water. The slime layer tends to increase in depth, forming an anaerobic layer where anaerobic bacteria can proliferate and produce many harmful substances. Such bacteria may be disease-causing bacteria which may have the ability to act upon the same substances as the beneficial bacteria of the biological filter, therefore masking the effectiveness of the beneficial bacteria. Thus, while ammonia and certain other contaminants may be converted into nontoxic products or in some instances removed by biological filtration, many other contaminants derived from these living filters can be introduced into the system.
Any essential or non-essential secondary organism (as hereinafter defined) will release to the environment a range of chemicals and substances due to that organism's growth, death and organic processes. These substances interact with the primary organism's released substances along with other created or converted substances to create an endless list of possible contaminants which concentrate in the system's environment, dooming the system to failure as a support environment for the primary organism within time. The constant interaction and changes in the chemistry of the environment result in the need for an organism to change or evolve to meet these new environmental conditions or the organism will fail or die. To maintain an organism at its current stage of evolution, all environmental conditions must remain the same or in a steady state. All contaminants released by the primary organism or its essential secondary organisms must be identified and removed thoroughly from the environment. The environment must be monitored to identify any unknown minor contaminants, which in time could alter the environment. These new contaminants must be removed from the system to maintain the primary organism of the closed system. Evolution should only occur through genetic change. If this change is undesirable, genetic manipulation or selective breeding can be introduced to correct the change. If the change is desired and created through genetic change or selective breeding and the desired change alters the environmental needs of the organism, then the steady state or extraction process can be modified to meet any new requirements.
In addition, the environmental conditions optimal for sustaining the primary organism for which the aquaculture system is established, e.g., fish of one or more species, but preferably a single species, may not be the same conditions optimal for the biological filter organisms (e.g., bacteria). Accordingly, effective biological filtration requires an environment suitable for the bacteria or other biological filter organism, which may be incompatible or even detrimental to the primary organism being cultivated. Thus, it becomes necessary to continuously alter the environment either for efficient primary organism growth or for efficient biological filtration or provide a single compromise environment suitable for both the primary organism and the biological filter at the expense of peak cultivation and filtration most beneficial to the primary organism.
The interaction between the primary organism targeted for cultivation in the aquaculture system and the biological filter or secondary organisms, their particular growth environments and their respective respiratory and other by-products creates, over time, a closed aquaculture system that is either doomed for failure or in need of total media replacement, such as exists in open systems.
The present invention overcomes the inefficiencies and deficiencies of the prior art by the virtue of an improved closed aquaculture system that is more reliable, simplifies the complex requirements of conventional systems and, by its ability to change with varying conditions, it lessens the likelihood of the system crashing.